On 06/08, Eric Paris wrote:
>
> On Wed, 2011-06-08 at 18:36 +0200, Oleg Nesterov wrote:
> > And I guess, all CONFIG_AUDITSYSCALL code in entry.S is only needed to
> > microoptimize the case when TIF_SYSCALL_AUDIT is the only reason for the
> > slow path. I wonder if it really makes the measureble difference...
>
> All I know is what Roland put in the changelog:
>
> Avoiding the iret return path when syscall audit is enabled helps
> performance a lot.
>
> I believe this was a result of Fedora starting auditd by default and
> then Linus bitching about how slow a null syscall in a tight loop was.
> It was an optimization for a microbenchmark. How much it affects things
> on a real syscall that does real work is probably going to be determined
> by how much work is done in the syscall.
and probably by how much work is done in audit_syscall_entry/exit.
OK. Thanks a lot Eric for your explanations.
Oleg.